Alterations of the oral microbiota in mild Alzheimer's disease and the appropriate application of chlorhexidine gluconate

Abstract

Objective: This study investigated the effect of 0.2 % chlorhexidine gluconate on oral microbiota dysbiosis in Alzheimer's disease (AD) and explored potential links between oral microbiota and cognition, offering new insights into its role in AD treatment.

Study design: We assessed the impact of 0.2 % chlorhexidine gluconate on the oral microbiota of patients with AD. One hundred patients were divided into two groups based on oral health score (using a cut-off of 8). Subgingival plaque samples were analyzed using 16S rRNA sequencing; no significant differences in bacterial composition were observed between groups at baseline.

Results: Poor oral health correlated with higher oral health scores (P = 0.000), fewer teeth (P = 0.002), lower cognitive levels (P = 0.048), and a higher proportion of patients with diabetes (P = 0.032). After 24 weeks of treatment with 0.2 % chlorhexidine gluconate in a randomized controlled trial, subgingival plaques from 66 patients showed changes in Porphyromonas, Filifactor, Desulfobulbus, Anaeroglobus, Pyramidobacter, Mycoplasma, Dialister, Fretibacterium, and Tannerella (P < 0.05). Treponema and Porphyromonas gingivalis were identified as potential interventional targets.

Conclusion: Chlorhexidine gluconate effectively alters oral flora, reducing harmful bacteria. Targeting specific microbiota disturbances may offer a promising strategy to delay AD onset or slow its progression.

Trial registration: This research was registered with the Chinese Clinical Trial Registry (ChiCTR; Reference: ChiCTR2000032876). Registered: 14th of May 2020; http://www.chictr.org.cn/showprojen.aspx?proj=53555.

Keywords: 16S rRNA; Alzheimer’s disease; Chlorhexidine gluconate; Neuroinflammation; Oral microbiota.

Fig. 1

Study design.Pre- and post-randomized controlled trial (RCT). The measurements were performed before and after intervention.

Fig. 2

Comparison of the preintervention oral microbiome of BOHSE≤8 and BOHSE>8 groups. (A) PCoA of oral microbiota in BOHSE≤8 and BOHSE>8 samples. (B) Heatmap of relative abundance between BOHSE≤8 and BOHSE>8 groups at the genus level.

Fig. 3

Comparison of the postintervention oral microbiome of intervention and control groups. (A) Balloon plot showing the results of the oral microbiota in intervention and control groups.(B) Shepard plot and NMDS plot of oral microbiota in intervention and control groups.(C) Extended error bar plot illustrating genera statistically different between intervention and control groups.